Automatic beam scanning apparatus for evaluating optical beacons

ABSTRACT

An automatic beam scanning apparatus is disclosed wherein a cylindrical open-ended chamber houses an optical beacon for evaluation. The chamber is rotatable about its longitudinal axis for determining the beacon beam intensity at selectable points off the axis of rotation. The chamber also is traversable in a path which sweeps a beacon beam over a detector. Hence, a predetermined rotate and sweep arrangement allows detection of the spatial energy distribution of the beam of an optical beacon.

United States Patent Peacher 1 Dec. 19, 1972 541 AUTOMATIC BEAM SCANNING3,532,432 10/1970 Mansour ..356/l21 APPARATUS FOR EVALUATING 2,381,5868/1945 Green ..356/12l OPTICAL BEACONS Appl. No.: 136,696

Primary Examiner-Ronald L. Wibert Assistant ExaminerV. P. McGrawAttorneyHarry M. Saragovitz, Edward J. Kelly, Herbert Berl and Jack W.Voigt [57] ABSTRACT An automatic beam scanning apparatus is disclosedwherein a cylindrical open-ended chamber houses an optical beacon forevaluation. The chamber is rotatable about longitudinal axis fordetermining the [51] Int. Cl ..G01 l/00, G01] l/42 beacon beam intensityat selectable points ff the axis [58] Fleld of Search "356/72, 222 ofrotation. The chamber also is traversable in a path which sweeps abeacon beam over a detector. Hence, [56] References cued a predeterminedrotate and sweep arrangement allows UNITED STATES PATENTS detection ofthe spatial energy distribution of the beam of an optical beacon.2,651,963 9/1953 Bischoff ..356/l2l 2,880,557 4/1959 Todd et al...356/l2l 4 Claims, 2 Drawing Figures CONTROL BOX 140 g TRAVERSE lROTATE M| MOTOR MOTOR 30 POT l 24 CHART RECORDER L POT 30 32 DECTECTOR22$ PATENTEDUEB 19 ran 3, 706. 498

CONTROL 4o POT CHART '4 RECORD POT J DECTECTOR \32 I FIG. I

no VAC M 9/ L 3 (R) O JOG (R) BY I. FIG 2 W Teddy J. Peocher, Kzcl lKlbgI 7/ lNvsoR. I

AUTOMATIC BEAM SCANNING APPARATUS FOR EVALUATING OPTICAL BEACONS SUMMARYOF THE INVENTION The present invention provides apparatus forautomatically scanning the beam of an optical beacon, which facilitatesevaluation of optical beacons by allowing rapid and facile determinationof the spatial energy distribution in the beam. A limit switch and relayarrangement allows the beacon output to be recorded, with the beaconposition being variable with respect to a fixed reference point. Anoptical detector is positioned in the plane of the beacon to be tested.A traverse table allows the beacon beam to be swept across the detectoror positioned at an angle with the detector. At any point in the sweeppath the beacon can be rotated around the longitudinal axis allowingoptical detection within the beam at a fixed radius from the opticalaxis of the beacon. Hence, rotation of a beacon directing a beamadjacent to a detector and traverse of the beacon across the detectorallows a recording of the spatial energy distribution in the beam.

An object of this invention is to provide apparatus for rapid and facilemeasurement of the spatial energy distribution in a optical beacon beam.

Another object of this invention is to facilitate evaluation or opticalbeacons by providing a selectable rotate and sweep pattern for detectingvariations of energy in a beacon beam.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic viewillustrating the principles of the invention, with extraneous structuralmembers omitted.

FIG. 2' is an electrical schematic of the rotate and traverse switchingarrangement for the structure of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, a housinghaving an openended cylindrical chamber 12 therethrough is mounted on atraverse table 14. Support structure 16 at each end of housing 10maintains the longitudinal axis 18 of the housing substantially parallelwith the plane of traverse table 14. Housing 10 is adapted for rotationaround axis 18 by conventional support means (not shown) between supportstructure 16 and the housing surface 10. An optical beacon 20 is mountedwithin chamber 12 with the optical axis thereof substantially alonglongitudinal axis 18. An optical detector 22, removed from the area oftraverse table 14, is positioned in the plane of axis 18 parallel withthe plane of the traverse table for receiving and responding to opticalenergy from beacon 20. Output electrical energy from detector 22iscoupled to a chart recorder 24 or other graphical recording means forrecording the spatial pattern of optical energy sensed by detector 22. Arotate motor M1 is mechanically coupled to housing 10 for rotatinghousing 10 and beacon 20 around the. longitudinal or optical axis 18. Atraverse motor M2 is mechanically coupled to traverse table 14 toprovide clockwise and counter-clockwise rotation thereof, enabling anoutput beam of beacon 20 to be swept across detector 22 in the plane ofaxis 18. Position potentiometers 30 and 32 5079 7..00 l lOdOl provide aseries of position peaks or timing marks for respective rotate andtraverse measurements. Typically, a potentiometer may be geared so that30 of beacon rotation provides 360 of potentiometer rotation. Hence,during every 30 of beacon rotation a mark or peak is provided by thelinear output of the potentiometer and the potentiometer starts overagain. Simultaneous recording of the output signals from detector 22 andpotentiometers 30 and 32 allows a cross section of the energy outputfrom the beacon beam to be identified. A control box 40 has outputsconnected to rotate motor M1 and traverse motor M2 for driving housing10 and traverse table 14. Control box 40 allows manual or automaticcontrol of the beam scanning procedure.

The electrical circuitry for controlling the beam scanning operation isshown in FIG. 2. Limit switches S1, S2, S3 and S4, not shown in FIG. 1,are springreturn switches mounted in the rotate and. traverse drivetrain pathand are actuated when the rotation has progressed througha'desired angle of rotation. The rotate motor M1 is coupled through aswitch and relay arrangement to the alternator current driving voltage.In a similar manner the traverse motor M2 is coupled through a currentdriving voltage. For manual operation of the rotate motor M1, selectorswitch S5 is placed in-the manual position allowing the driving voltageto be coupled to one side of a RUN switch S6 and to one side of a JOGswitch, these switches being connected in parallel. The other side of S6and the JOG switch is coupled to the blade of a single-pole, doublethrowswitch S7, for supplying forward or reverse voltages across the motor MIand thereby allowing clockwise or counter-clockwise rotation of housing10, depending on'the position of switch S7. Manual operation of thetraverse motor is identical to that for the rotate motor and is notshown. -Within control box 40, relays K1, K2, K3 and K4 are connected toallow automatic operation of the motors. Relay contacts have the samelabel as respective relays with a lower case letter thereafterdesignating individual relay contacts. Relay K4 is connected to a directcurrent power source B+ through a START switch. The START switch isshunted by a make contact K411 in series with closed limit switch S4. 8+is further connected through make contact K4d to common point 42" forproviding power to the remaining relays K1, K2 and K3. Relay K3 isconnected through the parallel combination of open limit switch S3 and amake. contact K3a to a common point 42. Relay K2 is connected. through aparallel combination of open limit switch S2 and a make contact K2b toone side of break contact'KElb, the other side of contact K3b beingconnected to common point 42. Relay K1" is connected through theparallel combination of open limit switch S1, make contact Klb, and makecontact K3c to one side of a break contact K2'c, the other side of K20being connected to common point 42. Operation of these relays inresponse to the momentary engagement of the START switch allowsautomatic beam scanning. to occur when selector switches S5 and S8 areplaced in the automatic position. Placing selector switch S5 in theautom'atic posb' tion allows ac. power to be coupledthrough'a-makecontact K4b, a break contact Kla, and a-break-make contactK2d to activate motor M 1. Break-makecontact motor MI that is obtainedby using switch S7 in manual operation. Similarly, with selector switchS8 in the automatic position ac voltage is connected through makecontact K40, make contact Klc, break contact K2a, and break-make contactK3d to activate motor M2 in the forward or reverse position. CapacitorsC1 and C2 are'respectively connected across rotate motor M1 and traversemotor M2 for providing arotating magnetic field. By switching acapacitor from one winding to another the field is reversed, reversingthe rotation of the motor.

In operation, a beacon under test is mounted in chamber 12 of rotatablehousing l with its optical axis coincident with the rotational axis 18.Limit switches S1, S2, S3 and S4 control the degree of rotation andtraversal of the beam along its optical path. The tra-verse table scanlimits can be set anywhere within 360. The rotate scan can be setanywhere within 720. By allowing the beacon to be rotated beyond 360during rotational scan, various traverse scan lines of the beam acrossthe detector are obtainable while still providing a full circle rotaryscan. Manual operation of both modes'is provided to recycle the unit orfor accomplishing short tests without utilizing the automatic operationmode, the JOG switch allowing incremental adjustment of 'beacon positionby momentary depression thereof. For purposes of explaining theoperation of automatic beam scanning, limit switch S1 is selected tooperate at 360 to stop Ml rotation and start M2 traversal, S2 ispositioned to stop traversal at 20 and start rotation. S3 is positionedto stop rotation at 450 and start traversal, S4 ispositioned to stoptraversal and end the test at 35. With these limits fixed, selectorswitches S5 and S8 are placed in the automatic position and the STARTswitch momentarily activated. Relay K4 is activated when the STARTswitch is momentarily closed and power is maintained thereto throughholding contact K4a. 8+ is supplied through closed contact K4d to point42 for future distribution' to relays K1, K2 and K3. Power is suppliedthrough selector switch S5 and make contact K4b to rotate motor M1 inthe forward or clockwise direction. Ml rotateshousing 10 and beacon 20through 360 around the axis 18. With the beacon optical axis initiallydirected approximately away from detector 22 during this 360 ofrotation, the beam intensity is measured at a given radius from theoptical axis thereof throughout the 360 of rotation. Limit switch S1 isactivated by the rotating housing 10 after 360 of rotation, allowing Klto be activated. Contact Kla breaks to terminate rotation of motor M1,and Klc makes to activate forward or clockwise rotation by motor M2.Rotation of motor M2 causes the beam of beacon to sweep across the faceof detector 22. When the beacon is 20 out of alignment with detector 22,limit switch S2 is activated. Activation of limit switch S2 allows K2 tobecome energized breaking the supply power to relay K1, opening thepower supply to traverse motor M2, and switching contacts K2d from theforward to reverse position for rotating beacon 20 in thecounter-clockwise direction. At this point relays K4 and K2 areenergized and relays K1 and K3 are de-energized. With the beacon nowdirected 20 out of alignment with detector 22 on the opposite side ofthe detector, beacon 20 rotates around axis 18 mime through 450. Thisallows detector 22 to obtain an additional sample of energy intensity atanother radius from axis 18 and sets up a traverse scan along a new scanline across the face of the beam. At 450 of rotation, limit switch S3 ismomentarily activated, and relay K3 receives activating power, beingheld operative through holding contact K3a. Contact K3bopensdeenergizing K2, contact K20 returnsv to the normally closed positionallowing K] to re-energize through K3c. Contact Kla breaks to stop M1rotation. Contact Klc makes, K211 returns to the normally closedposition and K3d goes to the normally open position to reverse the powerto motor M2, thereby reversing the direction of traversal of table 14.Table 14 then rotates in a counter-clockwise direction, again sweepingthe beacon beam across detector 22 until the beam is approximately fromthe detector. Limit switch S4 is then activated by the traversing table,opening the switch and removing power from relay K4. Deactivation ofrelay K4 removes holding power through'contact K4a, and B+ is removedfrom common point 42. Voltage-is removed from the traverse motor by theopening of contact K40, terminating testing of the beacon opticaloutput.

Obviously many possible variations of. scan pattern are obtainable byadjusting the traverse table scan limits and the rotate scan limits. Byallowing the'rotational motion to continue beyond 360 before contactinglimit switch 3, the return traverse scan of the beam axis across thedetector is along a different line in the cross-sectional plane of thebeam than was the first traverse' scan. For a uniformly illuminatingbeacon each recorded scan pattern should be substantially identical;however,.for the non-uniform beacon the degree of non-uniformity isreadily discovered and plotted. Thus for the instant example the beam isoriginally positioned at an angle 15 off center with the detector. It isthen rotated for 360 around the beam axis. This allows the beamintensity at a given distance off axis to be recorded. The beam is thentraversed across the detector to a point 20 off center on the other sideof the detector. This traversal allows measurement of the change inintensity diagonally across the beam along a given scan line. At 20 offaxis the detector has been moved relative to the axis by 5. The beam isagain rotated, this time through 450 to obtain another sample of energy.The intensity measured during rotation from 360 to 450 is a duplicate ofthat measured from 0 to and serves only to position the beam forsucceeding traverse scan. After rotation through the 450, the beam isagain traversed diagonally across the detector, terminating at an angle35 off center on the first or original side of the detector. Thistraversal has again swept the center of the beam across the detector;however, the scan across the beam is along a line normal to the firsttraversal.

Hence, the beam has been traversed across thedetector after 360 andafter 450 of rotation respecting the initial position prior to rotation.Intensity is therefore measured along mutually perpendicular axes acrossthe face of the beam and at two distinct radii from the intersection ofthese axes in the beam.

Obviously many modifications and variations of the present invention arepossible in light of the above teachings. It is to be understood,therefore, that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described hereinabove.

lclaim:

1. Automatic beam scanning apparatus for evaluating optical beaconscomprising: a housing having an open-ended cylindrical chambertherethrough and disposed for rotation about the longitudinal axisthereof, an optical beacon mounted within said chamber with the opticalaxis substantially along the chamber longitudinal axis, an opticaldetector adjustably positioned in a plane which includes said chamberlongitudinal axis and responsive to optical energy eminating from saidchamber to provide an electrical output signal, means for rotating saidchamber housing and beacon around said longitudinal axis for scanningthe beam of said beacon across said detector at a radius from saidoptical axis, a motor driven traverse table for traversing said chamberhousing and longitudinal axis within the plane of said detector and saidlongitudinal axis and thereby scanning through the center of the opticalbeam from said beacon across said detector, and recording meansresponsive to said detector output for recording the intensity ofradiant energy sampled thereby.

2. Automatic beam scanning apparatus as set forth in claim 1 whereinsaid rotating means is a rotate motor, and further comprising controlmeans coupled to said rotate motor and said traverse table motor forcontrolling the direction of rotation thereof.

3. In an automatic beam scanning apparatus having optical beacon mountedfor optical rotation about a beacon optical axis and supported fortraversal in the plane of the axis, the method of automatically samplingand recording the spatial distribution of the optical beam ofa beaconcomprising the steps of:

a. placing optical detecting means at an acute angle with the beaconoptical axis in a plane of said axis,

b. directing optical energy along said optical axis toward saiddetecting means,

c. rotating said beacon a predetermined angular distance around saidoptical axis for allowing said detector to sample radiant energytherefrom at a first radius around the beam axis,

d, scanning the center of said beam across said detector through anacute angle for sampling a first cross-section of radiant energy ofsaidbeam along a first scan line,

e. re-rotating said beacon a second angular distance around said opticalaxis for sampling radiant energy at a second radius around the beamaxis, and

f. re-scanning the center of said beam across said detector for samplingradiant energy along another scan line.

4. The method of automatically sampling and recording the spatialdistribution of the optical beam of a beacon as set forth in claim 3 andfurther comprising 4 the steps of:

a. recording a graph of said sampled energy during rotation and scanningof said beam of energy across said detector for determining spatialenergy distribution in said beam, and

b. repeatedly scanning the center of said beam across said detector atseparate and distinct positions of rotation for accurately determiningspatial distrlbution of energy across a cross-section of the beaconbeam.

l060ll 0076

1. Automatic beam scanning apparatus for evaluating optical beaconscomprising: a housing having an open-ended cylindrical chambertherethrough and disposed for rotation about the longitudinal axisthereof, an optical beacon mounted within said chamber with the opticalaxis substantially along the chamber longitudinal axis, an opticaldetector adjustably positioned in a plane which includes said chamberlongitudinal axis and responsive to optical energy eminating from saidchamber to provide an electrical output signal, means for rotating saidchamber housing and beacon around said longitudinal axis for scanningthe beam of said beacon across said detector at a radius from saidopTical axis, a motor driven traverse table for traversing said chamberhousing and longitudinal axis within the plane of said detector and saidlongitudinal axis and thereby scanning through the center of the opticalbeam from said beacon across said detector, and recording meansresponsive to said detector output for recording the intensity ofradiant energy sampled thereby.
 2. Automatic beam scanning apparatus asset forth in claim 1 wherein said rotating means is a rotate motor, andfurther comprising control means coupled to said rotate motor and saidtraverse table motor for controlling the direction of rotation thereof.3. In an automatic beam scanning apparatus having optical beacon mountedfor optical rotation about a beacon optical axis and supported fortraversal in the plane of the axis, the method of automatically samplingand recording the spatial distribution of the optical beam of a beaconcomprising the steps of: a. placing optical detecting means at an acuteangle with the beacon optical axis in a plane of said axis, b. directingoptical energy along said optical axis toward said detecting means, c.rotating said beacon a predetermined angular distance around saidoptical axis for allowing said detector to sample radiant energytherefrom at a first radius around the beam axis, d. scanning the centerof said beam across said detector through an acute angle for sampling afirst cross-section of radiant energy of said beam along a first scanline, e. re-rotating said beacon a second angular distance around saidoptical axis for sampling radiant energy at a second radius around thebeam axis, and f. re-scanning the center of said beam across saiddetector for sampling radiant energy along another scan line.
 4. Themethod of automatically sampling and recording the spatial distributionof the optical beam of a beacon as set forth in claim 3 and furthercomprising the steps of: a. recording a graph of said sampled energyduring rotation and scanning of said beam of energy across said detectorfor determining spatial energy distribution in said beam, and b.repeatedly scanning the center of said beam across said detector atseparate and distinct positions of rotation for accurately determiningspatial distribution of energy across a cross-section of the beaconbeam.